Dual clutch devices or multiple disk clutch devices are disclosed in the following U.S. patent documents: (a) U.S. Pat. No. 6,471,026 and U.S. Pat. No. 6,378,675; (b) U.S. Pat. No. 6,464,059; (c) U.S. Pat. No. 6,454,074 and U.S. Pat. No. 6,378,675; (d) U.S. Pat. No. 6,471,026; (e) U.S. Pat. No. 6,449,578; (f) U.S. Pat. No. 6,491,149; (g) U.S. Pat. No. 6,454,074, the disclosures of which are incorporated by reference in the disclosure of the present application. Further, in this connection reference is made to a clutch device disclosed in U.S. Pat. No. 5,887,690.
Disk clutch arrangements of the type mentioned above are generally wet clutch devices. As a rule, this type of wet clutch device has slotted lining disks and counter-disks without lining which are manufactured from steel, for example. Torque is introduced into the disk set, e.g., via the profile of an outer disk carrier in the outer disks, passes into the respective clutch arrangement to the inner disks and is conducted from there to the inner disk carrier, assuming a normal flow of force from the drive unit to the transmission. Alternatively, the clutch device can also be designed in such a way that the torque is conducted from inside to outside for this standard operating state.
In the designs of a wet dual clutch disclosed in the patent documents cited above, the lining disks of a radial outer clutch arrangement (outer clutch, for short) are associated with the outer disk carrier and the end disks of this “outer clutch” which define the disk set axially are formed by outer disks which are accordingly constructed with a lining on only one side. An advantage of this arrangement consists in that the lining disks with their slots are associated with the input side of the clutch device, that is, are driven directly by the drive unit, so that a conveying action is exerted on the cooling fluid, particularly cooling oil, when the transmission input shaft is stationary and the drive unit (engine) and, consequently, the outer disk carrier are rotating. This conveying action relies primarily on centrifugal force and reinforces the cooling of the clutch arrangement. On the other hand, a different allocation was chosen for the disks of the radial inner clutch arrangement (inner clutch, for short), wherein the outer disks associated with the input side are constructed without linings and the inner disks associated with the output side are constructed as lining-carrying disks.
It has been shown that while the ideas upon which the designs in these patent applications are based need not be revised, a high degree of stability is achieved in the clutch arrangement without such an allocation of the outer disks and inner disks for the radial outer clutch arrangement. That is, it has been shown that a sufficient cooling effect is achieved in the disk set even with out lined disks coupled on the drive side, so that there is no risk of “burning” the clutch arrangement at least for normal continuous and peak-load demands.